function p=newtonm_d(x,f1,f2)
% Search direction of Newton's method with the linear equation system
% solved with direct method;
% INPUT:
%       x - current iterate (n*1);
%       f1 - gradient (Rn->Rn) (n*1);
%       f2 - Hessian (Rn->Rn*n) (n*n);
% OUTPUT:
%       p - search direction (n*1);
% REVISION:
%       jqin, 15/feb/2011, created;
p=-f1(x)/f2(x);